1. Field of the Invention
This invention generally relates to a combination roll, and more particularly, to a roll unit for constituting the combination roll and the combination roll or roll assembly formed of a plurality of roll units.
The term "roll" used herein broadly means a member having a roll shaft and an outer peripheral contact or operative portion, which is integral, in operation, with the roll shaft so as to rotate conjointly with the roll shaft. The term "roll" herein used includes rolls employable in various machines for manufacturing, processing or using a sheet or film material such as a synthetic resin sheet or film, paper, etc. or various feed rolls or wind-up rolls usable in business machines, or print rolls.
2. Description of the Prior Art
Conventionally, various machines, for example, for handling a film or a sheet material of a synthetic resin, or paper or fabric, use rolls for winding up or feeding the material or the product.
In general, such rolls include a roll formed continuously and integrally and a combination roll which is formed of a plurality of roll portions in sections of short lengths, which are combined to form a roll assembly. These two kinds of rolls are chosen according to the uses or necessity. However, the continuous roll has such disadvantages that it can not cope with a change in width of the product; it is difficult to be manufactured and heavy in weight; it has a large contact area, which produces a large frictional resistance and accordingly causes, for example, wrinkles or static electricity on the product. Therefore, for the use in which these disadvantages do matter, a combination roll formed of a plurality of roll portions of short lengths, which is free from these problems, is chosen.
On the other hand, the roll portions of a short length constituting the conventional combination roll comprises a contact portion and a shaft inserting portion which are made of a synthetic resin or rubber and an insert member of a metallic material which is fitted in the shaft inserting portion. These roll portions must be mounted on and fixed to the roll shaft by setting screws into threaded holes formed in the metallic insert member for each of the roll portions.
Thus, in the conventional combination roll, a plurality of roll portions must be fixed to the roll shaft by setting the screws into the screw holes formed in the metallic insert member of the shaft inserting portion for each of the roll portions. Therefore, it is very troublesome or bothersome to mount or remove the roll portions onto or from the roll shaft. For this reason, it can not, after all, be easy to adjust the entire width of the roll even though the number of the roll portions is changeable.
Furthermore, as each of the roll portions constituting the combination roll is made of a synthetic material and a metallic material, the shaping of the roll portions and the insertion of the metallic insert member should be carried out in separate steps. This necessitates extra steps and costs for the manufacturing of the rolls.
The present invention has been made to obviate the above-mentioned problems, and it is in object of the present invention to provide a roll unit and a roll assembly, which are capable of simplifying the steps in fixing plural roll portions to a roll shaft and capable of facilitating the adjustment of the entire roll width of the combination roll, and capable of easily forming the roll portions only from, for example, a synthetic resin, reducing the weight of the roll portions.